1. Field of the Invention
The present invention relates to hydraulic retarding apparatuses in general and, more particularly, to a hydraulic energy dissipation system for a hydraulic, mechanical energy retarding apparatus.
2. Description of the Prior Art
In a typical hydraulic energy dissipation system of a hydraulic retarding apparatus, pressurized hydraulic fluid generated by a mechanical energy needed to be dissipated flows across a certain restriction. As the fluid flows across this restriction, there is a pressure drop while the flow remains constant. This drop in pressure represents a decrease in the hydraulic potential energy. In the absence of any mechanical work being done, the change in hydraulic potential energy results in an increase in a thermal (or heat) energy of the hydraulic fluid as it passes through the restriction.
Typically, this heat energy is dissipated into the environment through the use of an air/fluid heat exchanger (radiator). To increase the amount of heat energy dissipated in the heat exchanger, a device such as a cooling fan may be used to force air movement through the heat exchanger. The energy to drive the cooling fan may come from a variety of sources, including an electrical system, an engine, a vehicle motion, or some combination thereof. Also, in many cases the energy used to drive the cooling fan is a parasitic load on the vehicle system to which it is coupled. This parasitic load may have an undesirable effect of causing an overall efficiency loss.
Accordingly, it is the intent of this invention to overcome these shortcomings of the prior art by allowing for a portion of the hydraulic energy converted from the mechanical energy to be used to drive a hydraulic fan motor coupled to the cooling fan.